Improvement in machines for threading screws



4 Sheets Sheet 1.

F. P. SHELDON. MACHINE FOR THREADING SC'REWS.-

No.170,496. Patented. N'ov.,30,18'75.

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F. P. SHELDON. MACHINE FOR 'I'HREADING SCREWS.

Patented Nov 30, 1875.

-wyw N PETERS, PHOTULLITHDGRAPHERI WASEINGTON, D (I,

w 4 51:Lee1t;s---Sheec3 F P. SHELDON. 4 I MACHINE FOR THREADING SCREWS.

No.17 0,496. Patented. Nov. 30, 1875,

N-FETERS. FHQTO-LITHOGRAPHER, WASNINGTOIL D C,

F. P. SHELDON. MACHINE FOR THREADING SCREWS.

No."170,4:96. Patented Nov} 30,1875.

N.FE[ERS. PHOTO-LITHOGRAPNER WASHINGTON D C UNITED STATES PATENT *OE IOE.

FRANK P- SHELDON, OF PROVIDENCE, RHODE ISLAND.

IMPROVEMENT lN MACHINES FOR THREADING SCREWS.

Specification forming part of Letters Patent No. 170,496, dated Novembcr 30, 1875; application filed June 3, 1875.

To all whom it may concern:

Be it known that I, FRANK P. SHELDON, of the city and county of Providence, in the State of Rhode Island, have invented certain new and useful Improvements in Machines for Threading Screws; and I do hereby declare that the following specification, taken in connection with the drawings, making a part of the same, is a full, clear, and exact description thereof.

. Figure 1 is a perspective view of the complete organized machine, but the hopper which first receives'the screw-blanks in a mass is omitted for the-sake of clearness, and also because that part of the machine is already well known in the art Figs. 2, 3, 4., 5, 6, 7, and 8 are details of the machine to show the special points for more fully illustrating my invention.

- The machine belongs to that class of screwmaking machines which employ dies for cutting what are called fine-threaded or machine screws, as distinguished from coarsethreaded wood-screws, in which the thread is cut by a reciprocating chasing-tool.

. The first part of my invention relates to a means for insuring the presentation of the blank to be threaded to the stationary griping and holding jaws, so that the nick or slot in the head of the blank will always stand perpendicularly to the acting faces of the jaws, and thereby, affording the greatest resistance of the head to the gripe of the jaws, prevent the head from being crushed, as it is liable to be in machines of this class in case the blank is held with the nick standing parallel to the;

planes of the faces of the jaws.

. A is the rectangular bed or table .or' the machine. It is to be understood that some one of the many known automatic-feeding devices are to be employed, so that a single blank, a, Fig. 3, is able to be seized by the spring-fingers b, Fig. 1, whose ofice is to present the same to a pair of griping-jaws, to be by them held while the operation of cutting the thread 1 is being performed by a revolving die. Supposing now that a blank, a, Figs. 1 and 5, has been taken by the fingers, the first operation is for the fingers to move laterally toward a revolving yielding screw-driver, c. This movement is elfected by means of a spring, d, on

ment with the screw-driver.

of threadingthe blank. (lie, F, mounted on an arbor, F, which is the finger-shaft B, and controlled, as to time,

by the revolving cam e, the same finger-shaft cause the blank itself to rotate until such time as the side cam 0 moves the finger-shaft, and, consequently the fingers, away from engage- Theaction of the cam c is so timed as to leave the blank, when withdrawn from the screw-driver, with its nick standing in the proper position required to best withstand pressure when seized by the griping-jaws. The fingers are now permitted, in a well-understood way, to carry the blank in front of the griping-jaws E. These are stationary hold in g-clam ps, adapted to seize the blank by the headand hold it firmly, and are made to perform this office of seizing'and holding the blank, and releasing it after it has been threaded,-by their combination with toggle-levers E ,-sliding'sleeve E and revolving scroll-camE in a way well understood.

The next operation to be performed is that This is done by a made to revolve first in one direction, while the die is cutting the thread, and then in the reverse direction to enable it to back ofi' from the screw so made. There is nothing new in this operation, and the machinery by which it can be performed is familiar to all constructors of screw machinery. 1

In this instance, the side cam G, Figs. 3 and 4, acts upon an arm, G Fig. 3, set on the shaft G which latter is arranged on bearings so as to have an endwise movement. The for ward movement so given to the shaft G is communicated, by means of the arm G and adjustable screwhead h, to the die-arbor F, and the latter is thereby moved far enough to bring. the die up to the blank. The cam G continues to revolve for a sufficient length of time, (acting now as a leading ,camwith anv inclination of face corresponding with! the pitch of the threads on the die,) to enable the thread to be well started, when it ceases its action, and the springt' throws the shaft G to the position shown at Fig. 3, the die continuing its work.

The next part of my invention consists in the means by which the machine canbeadapted at pleasure to out different lengths of thread, and perform promptly the whole se-- quence of operations necessary to the threading of a blank, without being obliged to wait for any member of the machine to come to time, in case the machine is threading the.

shortest blank,over what would be necessary in case it were threading thelongest blank.

lnmachines of this class, as hitherto constructed,it is required, in order to cut screws of difl'erent lengths, to make changes in the cams or gears, or both, involving a greatloss of time, and complicating the machine with a large number ofchange-gears. The device presently to be described is independent of the rest of the machine, and may be applied to any screwmachine, when it is desired to, regulate, at will, the lengthof the thread to be out. The die-arbor or spindle F is'caused to rotate it alternately in opposite directions by means of the gear-wheels H H which are constan tly revolving in opposite directions, and

receive motionfrom the driving shaft H to which power is applied and an intermediate gear. The changes in the direction of rotation in the die-arbor are effected by means of a shifting-clutch, I, which is capable of slidingon the same shaft upon which the gears.

H 11! are mounted, and is madeto engage with 1 the one or the other by meansof clutch-pins.

Such clutch isconnectedwith the shai'tby means of a spline. Necessarily the gears H 11 are made to revolve around their shaft, ex-

cept atsnch timesas they are respectively locked therewith by means of the clutch I, which always revolves withthe shaft, and, consequently, the die-arbor will be rotated in one, direction or the other by meansof the gears J J according as the clutch I has locked the shat'twith the one or the other of the gears As already stated, the die-arbor F must have a longitudinal movement in its bearings,

toenable the die which it carries to traverse the part of the blank to be threaded, and, consequently, the connection of the die-arbor with gear J must be bya spline.

Now, to determine the length of time that the die-arbor shall rotate in the direction to enable the die to cut a thread, and to fix the time whenits direction of rotation'shall be reversed, there are employed thehereinafter-nextdescribed devices and combinations of instrumentalities. K, Fig. 3, is a sliding bar mounted in suitable guides in a frame, k, and is capable of a limited endwise movement, the extent of which can be regulated byadjustable stops. 1 Upon the underside of this*bar-aretwo brackets, k? 70 in whicli hthe adjusting screw-rod k is mounted. The bracket kfiprogjects downward lower than its fellow 70?, and this extended portion forms an ear-piece, which, with its fellow L-the latter being mounted on the screw-rod It, so that, itsdistance from k can be regulated at pleasure-constitute, in

combination wi h a collar or equivalent device on the die-arbor a part of? the, means for 'changin g the direction of rotation of the die% arbor. Upon the die-arbor or spindle F it will be observed there is placed a collar, M, theposition of which is adjustable, andwhich will partake of all the movements of the spindle,

and, will, at some time during the forward. movement of the die-arbor, while the die F is cutting a thread, come into contact with the ear-piece L, and will, also, during the reverse movement of the die-arbor, induced by the die unscrewing from thethread which it has out, come into contact=with the renew earpiece It. 'Upon approaches, and also two spring-latches, n1 n.

In combination with the upper side of the sliding bar,'as thus constructed, are two levers, N N, Fig. 3, having their fulcra at at a, Fig. 1. These levers are placed at such distance fromeach other, and in such a relation to the inclined approaches and spring-latches above mentioned, thatit is impossible for more than one of the levers to beresting: upon the: lower levelof theupper surface of thesliding bar at the same time. a From the ends of the levers N N" depend-two-.pins, 0 0 ,Fig. 3, by

means of links 0,and playsloosely in guides i ina block, 0, which latteris free to slide laterally upon a stud ppin.projectingflfrom the frame of the machinenfl Underneath thisslidin g block is a double' faced rotating cam.;l?, which, as it revolvesywill come into contact with that one of the pins 10$o which liesat; the moment within its path"of rotatiomand consequently Willi cause the block 0 to slide on itsstud-support topthe rightor to the left.

This block carries a clutch shifter, Q, which controls the clutchgear I, andth ereby the direction of rotatiouof the die-arbor. t

From the foregoing descrlptlon of theelementswhich compose this part of the organization of the machineit will be understood that the general mode of operationis as fol a lows: Suppose the die F to becuttinga thread upon a blank held by the jaws. TheclutchI and the die-arbor are being driven by the gear H When the die-arbor hastraversed sojfar forward as to bring the collarM infcontact with the ad just-ableear-piece L the sliding bar it It will then commeucetoslidein the same di-i rectionwith the die-arbor. This will cause the lever N to ridenp the inclined approach to the elevated section mot' the sliding bar, i the spring-latch niallowing this to beqnon r By this movement the pin o ehas been lifted clear of the revolving cam P. The continuing forward movement of the sliding'bar will the upper side of the sliding bar k is an elevated section, m,havingp-two inclined next cause the fellow lever N to drop off the abrupt face of the spring-latch n, wherebythe pin 0 will drop within the path of rotation of the cam P, and as a consequence of this the clutch I will" be shifted from engagement with the gear H into engagement with the gear .H, when a reverse movement of the die-arbor will commence.

It is obvious that the time during which the die-arbor shall rotate in the direction to enable the die to cut a thread, and consequently the length of the threaded portion of the blank, is under complete control by simply adjustin g the collar M and the ear-piece L prop-' erly with reference to each other. While the die is unscrewing from the threaded screw the die-arbor and its collar are moving longitudinally backward, and when near the end of its above described for the samepurpose can beapplied to screw-cutting machines in which the threading die does not revolve, but in which the die has only a to-and-fro movement, and the blank alone is revolved.

In order to give room between the face ofthe die and the holding-jaws for the insertion of another blank, a lever, B, Figs. 1, 2, and 8, actuated by the force of a spring or weight, presses against the face of the collar M, and slides the die-arbor farther backward in its bearings so soon as the die has backed off from the screw which has beencut.

Another feature of my invention resides in the factthat the devices by which successive. blanks are fed to the machine are permitted to remain at rest while a screw is being cut, but are started on the instant thatthe finished screw is ready to be discharged. 7

The several cams from which the necessary motions are obtained are shown at Fig. 4, and are all attached to a hollow shell, S, that, surrounds a shaft, S which latter is in constant revolution by gearing S deriving motion from the driving-shaft through a train of gears. The shell S is held locked when not in motion by means of a spring-arm, S Fig. 2, which engages with a notch in the cam S A sliding clutch, T, Fig. 4,,constantly revolving thecam lastmentioned has performed-itsoffice by means of a stop, it, set on .the frameof the machine with which a catch-pin, to, Fig. 2, engages. This catch-pin is set. loosely in. a

socket-hole through the shifter, and is con-' nected, by a link, to the end of the long arm of the lever U. The shorter armof thisle'ver is located so as to interfere with the pathof backward movement of the collar M on the die-arbor F, when the latter is-acted upon by the lever B for the purpose, as above explained, of moving the threading-die away from the jaws far enough to allow for the in-' sertion of a new blank. The back edge of the collar M is beveled so as topresent an-inclined plane to the side of theshort arm of the lever U, and, consequently, thebackwa-rd; movement of the collar will, by depressing the shorter arm of the lever, raise the catchfpinu u, and allow the spring 1* to cause the clutch to engage with the cam-shell. From this description it will be understood that the backward movement of the-d-ie-arbor which occurs just as the finished screw is ready to be discharged from the holdingjaws,

indicates the time when the feeding devices are to again be put into operation, and thereby any idle running-of the machine to bring the feeding devices to time incase. the ma chine is cutting short, instead of long,screws,. is avoided.

serted in the jaws,-and after the cutting-die, has taken hold of the same, the completed;

After a new blank has been inrevolution of the cam-shell causes the camface 8 to open the clutch-gear, when, nothing being in the way to prevent it, the catch-pin u will fall into engagement with the step-t, and the cam-shell will remain at rest.

the jaws, the die-arbor will immediately after-. ward be moved to its extreme backward limit by the spring-lever R, and, consequently, the feeding device will be at once put again into operation without waste of time, and the attendant can always tell from a distance Whether the machine isz-performing all its functions in their regular sequence by observing whether the feeding-fingers are in continuous movement. If they are, he knows that the machine is not threading blanks;

The device shown in is to lessen the severity of the blow on the gears when the direction of rotation of the die-arbor is reversed. It consists, essentially, of a frictionbrake, formed of 'two bands of leather held in two semicircular pieces of metal, which inclose the pulley V, whichis secured to. gear J, Fig. 1. The brakes are pressed together by a spring, a, Fig. 6. They are joined together and-attached to a rod, to, which passes through a hollow stand, W, fastened tothe frame of the machine. The rod w is encircled by. two spiral springs of equal length and tension, which press in opposite directions against the Washers on the-rod. The normal position of will be such that the springs are both equally closed. So soonas the pulley revolves in.

either direction, the friction of the brakes will cause the rod to be moved in one direction or another, compressing one of the springs until the tension of that spring is sufficient to balance the friction of the brakes. As soon as theclutch is disengaged from the gear which is driving it, this spring will suddenly be relieved, and will act upon therod and pulley V and start it in the opposite direction before the clutch has engaged with the other gear,

so that, when it does so engage with the gear which is rotating in the opposite direction, theblow on the gear and clutch-pins will be very much lighter. will work 'much smoother, and there will be less liability of breaking gears than would be the case if the clutch were suddenly thrown into a contrary motion'without preparation.

The device shown at Fig. 7 is designed to insure the discharge of the finished screw from the jaws, in case it sticks to either jaw from the effect of the severe gripe to which the.

blank is subjected. A bifurcated plate of thin metal, :12, Fig. l, is attached rigidly to the head of the mandrel which contains the jaws, and so that the two legs will act as stops to interfere with the screw as it is moved in the arc of a circle by the jaw to which it sticks as such jaw is opening, and thus will be stripped off the jaw.

a The bifurcated piece a; may be made movable, so as to be drawn out of the way of the .dies when cutting athread, close up to the jawsyand be brought into action only, just as the jaws open or a spring behind or between the jaws to press upon the head, might answer the purpose in same cases; but the form shown in the drawing I consider the more effectualand positive.

Another difficulty in die-machines which cut a thread nearly the whole length of the blank, is, that the chips of iron caused by the die will lodge on the jaws, and when they open will find their-way into the recess which fits around the headof the .blank, and when the jaws again close upon a. blank, the head 'will'be bruised by such chips and become spoiled. This has been overcome, (but only very imperfectly,) hitherto, in hand machinery, by the operatorwiping out thejaws by hand, after the cutting of every screw; and it consumes lunchtime, besides being very ineffectual.

- I make use of a stream ofsome suitable liquid which is delivered from a pipe, y, Fig. 3, upon the outer'surface of the jaws before they open, thus washing off the chips which have lodged thereon, so that when the jaws open there will be no chips there to fallin. I make use of oil, because the streainof oil is necessary as a lubricator of the dies in cutting the thread, and by having the oil-pipe hung on a swivel-joint and pressed against the head of the die-spindle by a spring, 2, it serves the doublepurpose of lubricating dies, and of washing the jaws.

And thus the machine I wish it to be understood that I do not limit it myself to the construction and arrangement of the several parts of the machinery compose ing the subjects of my invention, as described, but intend to include all more formal variations of structure and arrangement accomplishing the same mode of operationby equivalent means.

What I claim as my invention,and desire to secure by Letters Patent, is-'- 1. The combination of the following instrumentalities for causing the nick in the head of a screw-blank to be set in a given position before presentation to the holding-jaws, viz;

a suitable feeding mechanism. for selecting blanksone by one, b, holding-jaws E E, and a revolving blank-turner, c,substantially as de-.

scribed.

2. The combination of the spring-fingers b, arranged to be capable of a sidewise movement, as described, with a revolving blankturner, c, for enabling the screw-blank to become engaged with the blank-turner, and at:

terward be disengaged therefrom, as specified. 3. The combination of the following instrumentalities for changing the backingofl' motion, after the threaded screw is clear of the dies, to the motion for threading the next blank, viz: an adjustable collar, M, partaking of the longitudinal movement of the dieholder, a shifting-clutch,[, operated by suitable mechanism, as described, and the revolving gear H inducing, by suitable gearing, the requisite rotationfor cutting the thread, substantially as specified.

4. The combinationof a sliding bar,-K, having ear-pieces k L, as described, an adjustable collar, M, partaking of the longitudinal motion of the die-holder, a shifting-clutch, I, operated by the cam P, and alternately engaging pins 0 0 at the times determined by the said sliding bar and collar, and gears H H revolving in opposite directions, substantially as described, for the purpose of automatically changing the direction of rotation of the die-arbor, as specified.

5. The combination of the sliding bar K,

constructed as described, the levers N N, and

the spring-latches n a, substantially as speci- 6. The combination of the adjustable collar M, partaking of the longitudinal motion of the die-holder, with the system of cams on the hollow shaft S, by means of a vibrating clutch-gear connecting such shaft with the. source of motion, and the lever U, control-- ling a stop-catch, u t, whereby the said camshaft may be stopped while'a blank is under the action of the cutting-die, and be started again after a blank has been discharged from the jaws, or in case a blank has. not been presented to the die, substantially as described.

7. In combination with the gears J J, whose .direction of rotation is alternately changing to reverse the motion of thefdie-arbor, the friction-pulley V, and doublewacting springbrakes, described, for giving an easy initial movement to the gearing for changing direction, substantially as specified.

8. The combination, in an automatic screwthreading machine, of the bifurcated discharger, the griping-jaws, and the feeding-fingers, arranged and operating together substantially as described, whereby the finished screw is ejected from the jaws, and the way cleared for the advance of the fingers with a blank, as set forth.

9. The combination, substantially as described, of the feeding-fingers b b, with the stationary holding-jaws E E, when the latter are arranged to open in a plane which is intersected by the path of movement of the fin-' gers, whereby the blank can be presented so as to be griped by the jaws without the requirement of any sidewise movement on the part of the fingers.

FRANK P. SHELDON. Witnesses:

THOMAS F. COSGROVE,

J. O. B. Woons. 

